Dolby Laboratory Training Notebook

Dolby Laboratory Training Notebook

I’m midway through a training session with Dolby Laboratories rep Matt Kanau. Matt has tuned close to 3,000 theaters and has worked for Skywalker and Lucasfilm for 9 years. He is now the full time Dolby rep for West Coast Canada.

Matt has been going over in detail:
Room Acoustics:
*RT 60 Design Specifications
*Dialogue Intelligibility
*Acoustical Model normalized for 500Hz

Reverberant Characteristics
* Smooth Decay

Room Volume
*How the 500Hz Decay time is determined

How RT 60 is measured
*Multiple Mic Locations
*Steady Pink Noise
*Average
*High Spls from 31Hz to 8kHz
*Extrapolation

Background Noise
*Must be low to avoid mashing quiet sound effects.
*NC-30 highs acceptable

Translation of Dubbing stage to Playback environment
*Room Acoustics
*Low Background Noise
*45 degree Monitor at Mix
*Isolation
*High Quality Sound components
*System setup and calibration/Alignment
How Background Noise is Measured

NC Standards
*Cinemas – 25
*Dub – 20
*Foley – 5 to 10

Monitoring Angles
*45 degrees

Isolation from Noise Sources

Sound System Components

*Loudspeakers
*PowerAmps
*Crossovers
*EQs
*Other processing
*Perforated screens Screen
Sound System Calibration

Equalization Standards
*How do we decide what EQ to apply to all speakers
*Study room, look for patterns
*Let Reverberation play a role
*Consider room size
*Using the ear

-The X-Curve-

-Beginning Training on the 3Ds:

Dolby Digital – VBR – Variable Bit Rate – AC3 – 12:1 Compression

Basic Data Streams: The 3Ds:
Dialog Normalization – A measurement of all peaks of Dialog in the Mix. Dolby decided that -31dbfs is the standard playback of AC3 files.
Dynamic Range Control – Presets in Metadata – Line Mode Compression – RF Mode Compression:
Listening to 5.1 Mix
Modulates Frequencies
Stereo Compressor
Down Mixing: AC3 down mixed to Stereo means the removal of the LFE. ALl discrete LFE information is stripped from the mix.
6 Down mixing presets:
1) Film Light
2) Film Standard
3) Music Light
5) Music Standard
6) Speech

– John

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